Conventionally, temperature is an important parameter in material development. In vacuum processing of vapor-deposition performance on a substrate being heated, an approach in which the light of a heater is condensed using a heating wire or an infrared lamp is generally employed for heating. However, this conventional method has problems that make it difficult to heat a substrate to 1000° C. or higher. Sample problems that hinder temperature increase include heater disconnections or film adhesion and formation on the condenser lens used for the lamp (particularly in processes such as CVD that require high pressure). In order to heat a substrate to 1000° C. or higher, special heater with a carbon or SiC resistor is employed; heating graphite by heat induction has also been attempted. However, since the carbon heater itself is highly susceptible to oxidation and a reducing atmosphere, the surface of the carbon heater must be coated with an atmosphere-resistant substance such as BN. On the other hand, the heat induction system has other problems, such as an inability to use a metal chamber, complicated substrate conveyance, and low degree of design freedom.
A laser heater (Patent Document 1) that uses a high output laser as a heat source has been proposed as a means to solve the aforementioned problems.
However, even though the laser heater guides the laser beam is guided to an area near a substrate by means of an optical fiber, a thin film also adheres to the end face of the fiber during the thin film deposition process, such as the CVD method, which requires a relatively high pressure (several mTorr or higher) since the end face of the optical fiber is exposed in a thin-film forming device. As a result, the laser output and hence temperature decreases and the laser body is damaged by the reflected light.
Patent Document 1: Japanese Patent No. 3268443